A Basic Primer on Endurance Training

by Charles Staley BS, MSS

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Although many anaerobic athletes often eschew the concept of endurance training altogether, in fact, ALL athletes must have the capacity to endure their event(s), no matter how brief or long that might be.

However, for the gym-hardened anaerobicists among us, delving into the World of endurance theory can be daunting, to say the least! In the same way that gym discussions revolve around concepts like "one rep max," "motor unit recruitment," "neural drive," and "eccentrics," endurance athletes possess a comprehensive nomenclature of their own including such verbiage as "V02Max," "lactate threshold," "oxygen debt," and "aerobic base," to name just a few.

So whether you’re a competitive athlete looking for the best way to stay sharp in late rounds, or a recreational bodybuilder searching for a way to incorporate aerobic exercise to accelerate fat-loss, my objective is to provide you with the basic theory and concepts of endurance training. I think you’ll find that these concepts are not as intimidating as they first seem. And in fact, a deeper appreciation of the benefits of endurance work may even tempt you to lace up those Nike’s and head out for a quick 5 miles (Ok, maybe I’ll accept 1/4 mile if you weigh more than 200 pounds)!

Definitions

Let’s get the ball rolling by considering a few basic definitions.

Endurance is the ability of being able to maintain a high quality of work in the face of fatigue. All athletic skills and events require endurance to some extent, however, the energy requirements of extremely brief skills (such as a single punch, for example) are normally met with ease.

Anaerobic endurance refers to short term endurance capacity which relies mainly on anaerobic energy pathways. Aerobic endurance, on the other hand, refers to longer-term activities which rely primarily on the oxidative energy pathway.

There is no definitive border between anaerobic and aerobic activity, and in fact, all activities are fueled by both pathways. So when we refer to something being "aerobic" or "anaerobic," we’re referring to the pathway that is the primary contributor of energy for that activity. Normally, short, intensive activities lasting less than say, 90 seconds, might be though of as "anaerobic," while longer, less intensive work is though of as "aerobic." Also, longer activities which are intermittent (i.e., boxing, football, etc.) are also thought of as "anaerobic," since they consist of repeated high-intensity bouts of activity.

V02Max: Your Ability to Utilize Oxygen

Whenever athletes discuss endurance capacity, the term "V02 max" (or "max 02") comes up. V02 max is a measure of how much oxygen you can consume and use aerobically, and is specified as milliliters of oxygen per kilogram of bodyweight per minute, or mls/kg/min. Although athletes with a higher V02 max have a greater potential capacity to use oxygen aerobically, (and, by inference, should have better endurance abilities), in reality, there’s a significant difference between your aerobic capacity (as determined by your V02 max) and your actual endurance performance ability, which is more often limited by something called your lactate threshold. A big VO2 max determines the ceiling for the athlete’s sustainable work rate— it is a measure of the size of his or her "engine." However, it is the lactate threshold that determines the actual percentage of that engine power that can be used continuously. Let’s explore...

The Lactate Threshold

When your muscles perform intense work, they produce a waste product called lactic acid. This lactic acid is familiar to anyone who’s experienced an intense muscular burn after performing a hard sprint or an extended set of bench presses in the gym.

Up to a point, your body can "clear" this lactic acid by using it up as fuel for energy (which is called "oxidation."). This point is the definition of lactate threshold. If you’re working at a low-enough intensity, your body will be capable of clearing the lactic acid "on the fly" and you will be able to continue indefinitely (in theory, at least). This is called "aerobic endurance." If, on the other hand, you are working at a high-enough percentage of your maximal abilities, you’ll produce so much lactic acid that your body will be unable to clear it, unless you reduce your work output or stop altogether, allowing your body’s aerobic processes to clear the lactic acid. This process is sometimes called "oxygen debt," because, although you can work very hard without oxygen for a brief period, at some point you’ll have to stop and undergo heavy respiration as a "pay back" for your body.

According to Jerry Robinson and Frank Carrino in their text Max 02, The Complete Guide to Synergistic Aerobic Training, the average sedentary person has a V02 max anywhere between 20 and 40 mls/kg/min and a lactate threshold at about 50% of their V02 max. Of course, well-trained endurance athletes have much higher V02 max scores (please see Table 1), with lactate thresholds approaching 80 or even 90 percent of their V02 max. So this means that athletes who wish to improve their endurance performance capabilities can either train to improve their V02 max, their lactate threshold, or both.

Table 1: Average Maximal Oxygen Uptakes of Team National Athletes 

(Maximal uptake in athletes, B. Saltin & P. Astrand, Journal of Applied Physiology, V 23 #3: 353-358, Sept., 1967.

Smart athletes work on both aspects in their training, although we do know that most people can only hope to improve their V02 max about 20-40 percent over an entire athletic career. In other words, there are more significant genetic restraints on V02 max than there are on improving lactate threshold. It should be obvious by now that an athlete with a lower V02 max, but a higher lactate threshold can have a better endurance performance than a peer with a higher V02 max but a lower lactate threshold. Let’s examine a hypothetical comparison for the purposes of illustration:

* Measured as milliliters of oxygen per kilogram of bodyweight per minute (mls/kg/min).

As you can see, Jenna, who may have significant genetic limitations on V02max, has still managed to develop a superior endurance performance capacity compared to Marilyn by raising her lactate threshold.

The Periodization of Endurance Training

In a periodized training program, it’s important to develop your V02max, improve your lactate threshold, and also the third aspect of endurance development, technical efficiency, which basically means that you need to refine your technical skills to the utmost. Let’s examine each phase independently, and in the order that they appear in your training cycle.

Phase I: Develop the Foundation (Improve V02 max)

The accumulation of training volume early in the macrocycle is known as laying down an "aerobic base." This aerobic foundation is what creates the necessary "machinery" which will serve to create a better anaerobic working capacity later in the cycle— in other words, as your aerobic fitness improves, you’ll be able to work harder and longer before reaching your lactate threshold.

Note: Many conditioning specialists eschew the concept of developing an aerobic base, feeling that a highly developed aerobic capacity is counter-productive to the attainment of speed and strength. However the anaerobic system is based on the aerobic system, so at least in principle, it seems logical to develop the system which will promote lactic acid clearance during high intensity training efforts later in the cycle. As in all things, it really is an issue of how much aerobic work is done, and where it is placed in the training cycle.

When attempting to develop or improve your aerobic capacity, training should take place between 3 and 6 days a week. The total duration of work in each session might be anywhere from 10 minutes to an hour or more— longer durations are inappropriate for athletes, unless they expect their competitive event to require more than 30-45 minutes of continuous activity.

The intensity of training should, by definition, be low (if it was high intensity, it would be anaerobic, not aerobic). Although many heart-rate formulas have been used with success, I have found the age-old "talk test" to be more than accurate: if you can carry on a conversation during the aerobic workout, your intensity isn’t excessive. If you can’t, reduce the intensity until you can— save super-intense training for the anaerobic interval phase later in the training cycle. Remember— we’re not trying to raise the lactate threshold— yet. We’re simply developing the foundation...the peak will be added later. One last point: as you progress through the macrocycle, the content of your aerobic activities should gradually progress from a wide selection of different activities, to a smaller, more specific group or activities. For example, when establishing an aerobic base, you might cycle on Monday, Swim on Tuesday, run on Wednesday, and so forth.

When it comes to aerobic training, "the more is better" philosophy that so many athletes have can be counter-productive, particularly with regards to strength and body composition, as the following research findings indicate:

• According to a recent study presented in IDEA magazine, the average female aerobics instructor has 18% bodyfat. This is higher than the average female competitive weightlifter (16%).
• According to a recent study published in Muscular Development magazine, muscle necrosis (tissue death) and inflammation can be observed in the calves of marathon runners seven days after a race.
• According to Dr. Marc Breehl, a leading anesthesiologist specializing in cardiac surgery, the enlarged hearts of aerobic athletes are weaker, not stronger than those with anaerobic backgrounds.

So, the idea is to "get the most bang for your buck" by doing as much aerobic training as it takes to maximize your aerobic capacities, but also to stop when you’re experiencing diminishing returns. If you do too much aerobic exercise, at too hard a pace, you’ll impair your strength training sessions, and have a difficult time recovering from your training program.

Two Hypothetical 8-Week Aerobic Endurance Training Programs

These two programs illustrate the two basic ways that aerobic endurance programs can be constructed— "steady-state," which means that you perform a single bout of continuous activity (at the highest heart rate that you can manage for the entire duration), and "aerobic-interval training," which utilizes a handful of shorter bouts, separated by short rests. Although both options can be used by any athlete, the aerobic-interval method is more appropriate for experienced athletes, since the shorter durations allow for higher heart rates which are obviously more stressful than the steady-state method. Another option is to first use the steady-state program, followed by the aerobic-interval program, which serve as an intermediate-intensity zone leading up to the anaerobic intervals to follow later in the macrocycle. For the sake of clarity, both programs involve exactly the same overall volume of training, as measured by time.

Aerobic Endurance Training Modalities

Steady-state method:

Aerobic-interval method:
(Note: rest intervals are always 1/2 the duration of the work intervals being performed that day)

Phase 2: Anaerobic Interval Training

Once you’ve developed the highest amount of aerobic efficiency possible within the confines of your training cycle, it’s time to throttle back a bit on your training volume to make way for anaerobic interval training for the purpose of raising your lactate threshold. The aerobic base that you have just established will now be down-shifted to "maintenance" level by reducing the total volume of aerobic training considerably— down to between 25 and 50 percent of the original volume. Your efforts will now be dedicated primarily to improving your ability to tolerate lactic acid buildup, which is really a more significant limiting factor than aerobic capacity for most athletes.

An interval is defined as a period of time or a specified distance. For athletes, it means repeated bouts of high intensity exercise with intermittent rest periods. Since the 1960's, interval training has come to be thought of as the key to endurance performance success. In some training programs, it accounts for 50-75% of the total training volume.

Intermittent exercise allows a higher total volume of high intensity work, and also accumulates a greater volume of stress on the blood pumping capacity of the heart. According to exercise physiologist Dr. Steven Seilor, the periodic elevations and decreases in intensity may create special loading stresses on the heart that are adaptive. Seilor suggests that during an interval, heart rate climbs high, then at the moment you stop the interval, heart rate immediately starts to drop, but venous return remains high. These exposures to additional ventricular stretch may help trigger ventricular remodeling (increased heart ventricle volume).

This phase of your endurance training program should be tailored to the actual event duration that you’ll be expected to endure. If you’re a kickboxer entering a match composed of (6) 2 minute rounds, there’s no point in engaging in 3 hour runs to improve your endurance for the fight!

In fact, even if you decide to employ 20 minute intervals with 5 minute rests between intervals, you’d be using ten times the volume that you’ll experience in the upcoming fight! If you think that this will improve your "wind," you’d be dead wrong, because you’ll be training the wrong energy system for the job. It would be like trying to improve your 100 meter speed by running 1000-meter intervals!

When performing anaerobic intervals, you need to be working hard— as hard as possible, for the duration of each interval. But perhaps more importantly, you need to focus on the quality of what you’re doing. After all, what’s the point of doing repeated 2 minute intervals on the heavy bag if your technique is atrocious? Although I will present two hypothetical programs for anaerobic training below, always make modifications as needed based on your present performance capacity. For example, if you can’t go "all out" with an opponent for 30 seconds without falling apart, neither of the following programs will be appropriate, and you’ll have to reduce the duration of the intervals, at least for now. The rule-of-thumb is: first establish quality, then increase quantity.

Two Hypothetical Anaerobic Interval Training Programs

Let’s look at two athletes, one with better strength than endurance, and the other with better endurance than strength. We now have 8 weeks to go before the fight. Here is a hypothetical interval training program for each athlete:

Athlete is strong, but needs better short-term endurance:

As the above scenarios indicate, strength is developed by performing intervals which are slightly shorter than the competitive event-duration, while endurance is developed by performing slightly longer intervals. No not blindly copy the above programs, but instead, learn to apply them to your specific situation.

Unlike the aerobic build-up period, the activities you’ll perform must be much more event-specific during this phase. Use primarily competitive skills and skill-elements in a controlled, yet challenging environment to prevent injury in the final weeks leading up to an event. Athletes can spar with safety equipment or by handicapping themselves, for example, rotating opponents to keep them fresh. Another example of a handicap is to spar without using a favorite technique, which will force you to develop your weaknesses.

To this point, I’ve said that high level endurance performance depends on

1. a high VO2 max, and 
2. a high lactate threshold.

 Your VO2 max sets the upper limit for your sustainable work potential. The lactate threshold indicates how much of your cardiovascular capacity you can take advantage of in a sustained effort. Multiplying VO2 max by your lactate threshold gives us a measure of the size of your "endurance engine." In sport, however, victory does not automatically go to the athlete with the biggest engine. Efficiency (or technical skill) is critical to maximizing performance capacity. You might have a V02max of 85 and a lactate threshold of 90%, but if, during a sport training session, you waste precious energy by attempting techniques from poor positions of leverage, or made bad tactical and/or strategic decisions, it’s all for naught! In other words, from a functional perspective, improving your technical and tactical skills improves your ability to endure, since you are moving with better efficiency.

Final Thoughts

Athletes need to make the distinction between doing endurance training for the purpose of improving endurance, and doing such workouts as a tool to improve body composition. In the latter instance (which will be most applicable for Mesomorphosis readers), both aerobic and anaerobic variants are viable tools when used judiciously and in the proper proportions. Aerobic work, when performed at low intensities, are valuable in assisting recovery from intense workouts. Anaerobic interval training, when done at or near lactate threshold, assists in fat loss through the production of growth hormone levels.

Strangely, moderate intensity endurance training seems to be most counter-productive for athletes interested in improving body composition— they wear you down without producing the hormonal environment conducive to fat loss.

In the final analysis, I’ll leave you with a concept that always holds my clients in good stead: when making decisions about training load, strive to the least amount of work that will lead to a result, rather than the most.

Seek to become efficient with your training efforts. Avoid waste— any training program that leads to results will also lead to injury if followed to long and/or too repetitively.